Various types of micro-electro mechanical systems (MEMS) are known. Such devices perform a number of functions including, but in no way limited to, switches, actuators, and light modulators. MEMS functioning as spatial light modulators (SLMs) include pixels formed of electrically addressable, deflectable mirrors or reflectors. SLMs are transducers capable of modulating incident light in correspondence to an electrical and/or optical input. SLMs are capable of modulating the incident light in phase, intensity, polarization, and/or direction.
Additionally, MEMS may function as Fabry-Perot light modulators. Fabry-Perot light modulators include parallel mirrors. One of the parallel mirrors is modulated to change the gap between the mirrors. The gap between the mirrors determines the wavelengths which will be allowed to exit the device.
In general, MEMS typically include a deflectable or movable mass or surface coupled to a substrate by a resiliently deformable member, such as a flexure or a spring. The resiliently deformable members typically position the deflectable or movable mass, such as a reflective surface or mirror, in a neutral position. The neutral position may be parallel or not parallel to a coupled substrate. The resiliently deformable member will keep the deflectable or movable mass in the neutral position until the selective application of attractive electrostatic forces or repulsive forces due to some other means, causes a deflection thereof. In the context of SLMs, even slight deflections of the mirrors or other reflectors may dramatically alter the modulation of light incident thereon.
Movement of a movable mass deforms the resiliently deformable members, storing potential energy therein. The stored potential energy tends to return the deflectable or movable mass to its neutral position once the electrostatic force is removed. The resiliently deformable members are known to deform in a cantilever mode, in a torsional mode, or in a combination of both modes known as the flexure mode.
Repeated deflection of traditional resiliently deformable members results in a phenomenon known as creep. Creep is a relaxation or deformation of the resiliently deformable members that results in improper operation of the MEMS. For example, a relaxed resiliently deformable member may be incapable of returning a deflectable or movable mass to its proper neutral position when electrostatic forces are removed, resulting in changed or degraded performance of the MEMS over time, such as unintended modulation of light.